1. Field of the Invention
The present invention relates to a distance acquisition device, more particularly to a distance acquisition device, and a lens correcting system and method applying the distance acquisition device.
2. Description of the Related Art
Generally, in multimedia applications, images are captured using a lens and are subsequently subjected to processing by electronic circuits. Such applications may include portable digital cameras, web cameras, and mobile phones with image-capturing capability.
Non-planar lenses are often used for capturing images with required viewing angles. However, such lenses generally exhibit non-uniform optical characteristics (e.g., optical vignetting) at various relative positions thereof, which are unacceptable in certain high-quality applications. Conventional techniques for correcting such non-uniform optical characteristics generally include the process of adjusting brightness of each pixel of an image based on a distance between the pixel and the center of the image.
Specifically, in a Cartesian coordinate system, the distance between any two points may be obtained through the following equation:d=√{square root over ((x1−x0)2+(y1−y0)2)}{square root over ((x1−x0)2+(y1−y0)2)}
wherein (x0, y0) represents the coordinates of one of the points, (x1, y1) represents the coordinates of the other of the points, and d represents the distance between the points.
Hardware implementation of such a mathematical equation requires three adders, two multipliers, and a square root extractor. However, obtaining a distance for each pixel of the image from the center of the image through the hardware implementation of the aforesaid equation will result in high circuit costs.